Frans georg liljenroth



July 24, 1928. 1,678,518

F. G. LILJENROTH PROCESS OF MAKING A MIXTURE 0F NITROGEN AND- HYDROGEN Filed Oct. 17. 1922 Patented July 24, 1928.

UNITED. STATES PATENT'ONFFI'CE.

FRANS GEORG LIIJENROTH, OF S'IOCKSUND,-' SWEDEN.

PROCESS OF MAKING A MIXTURE OF NITROGEN AND HYDROGEN.

' Application filed 0ctober17, 1922, Serial No. 595 171, and in Sweden December 3, 1921.

This invention relates to an improved method of producing a mixture of nitrogen and hydrogen.

Hydrogen was hitherto-produced ma large scale either by electrolytlcally decomposing water or by reducing steam by means of mcandescent coke in water gas generators. The first-mentioned method has the advantage that pure hydro enis at once produced but at the same time has the draw- 7 back that an expensive plant and an ample supply of cheap electric power are required. The latter method does not roduce immediately pure hydrogen gas ut so-called water gas which consists of a mixture of equal volumes of hydrogen and carbon monoxide. The latter constituent can, however, easily be converted by acatalytical process by means of steam into carbon dioxide and the mixture then be purified by removing the carbon dioxide, the resulting product being essentially pure hydrogen gas.

The water gas reaction, as is well known, is endothermic and heat must be supplied in some convenient manner. Usually this is effected by combusting a part of the coke the gas generator by means of -atmospher1c oxygen. If the supply of the a rtakes place simultaneously with the reductlon of the steam a gas is obtained which is diluted by at least 50% by volume of nitrogen, such gas being suitable for heat or power generation only but not for the synthetic production of ammonia. For the latter purpose theoretically a gas mixture of by volume of hydrogen and 25% by volume of nitrogen 1s needed. For obtaining a gas having such small percentage of nitrogen the, gas generator-must be operated in such manner that the air and the steam are supplied alternately to the generator and the combustion gases when supplying the air be removed. The process with an alternating supply of air and steam is, however,.essentially less economical than a continuous process based on a simultaneous supply of air and steam.

The object of this invention is to improve the continuous water gas process in such manner that it can be used for producing in an economical manner a mixture of hydrogen and nitrogen suitable for the synthetic manufacture of ammonia.

The invention consists, chiefly, in combining the producing of hydrogen by means of the water gas pfocess and subse uent reac tion upon the carbon monoxide o the water gas by means of steam-with the electrolysis of water in such manner that the generation of the water gas is effected by. means of the electrolytically produced oxygen together with steam and atmospheric air in such regu- Carbon monoxide Carbon dloxide i Nitrogen 50 A gas mixture of such composition cannot Per cent. 7

be used for the synthetic manufactureof ammonia. For increasing the percentage of hydrogen and utilizing the carbon monoxide the latter constituent is generally oxidized by catalytic re-action with steam whereupon the carbon dioxide is removed. The resulting gas. mixture consists then of. about 45 parts by volume of hydrogen and 50 parts by volume of nitrogen. Also such gas mixture is unsuitable for the synthetic producing of ammonia. For adjusting the-proportionsso as to obtain the ratio of 3H, N re nestedfor the manufacture of ammonia an a dition of 105 parts by volume of hydrogen would evidently be necessary. The producing of such large quantities of hydrogen by other processes, for instance by electrolysis, would not be economical. For avoiding said drawback I produce'a water gas containing less than 50% but more than 25%0f nitrogen and a corresponding higher percentage of hydrogen and carbon monoxide. The carbon monoxide of said water gas is then in well-known manner oxidized by acatalytic re-action with steam and the carbon dioxide removed. The proportions of electrolytic oxygen, atmospheric air and steam used for the water gas process are so related to each other that the percentage of nitrogen supplied by the air is substantially one third of the hydrogen obtained from the water gas together with the electrolytic hydrogen. When the electrolytic hydrogen then is added to the purified mixture of hydrogen and nitrogen obtained from the water gas a gas mixture is obtained which consists of hydrogen and nitrogen substantially in the ratio 3 1 as requested for the synthetic manufacture. of ammonia. A-ralculation shows that it generally willbe suflicient to produce, about one fourth to about one third of the total quantity of hydrogen by electrolysis while the remainder is obtained from water gas produced by utilizing the electrolytic it will. be possible to produce economically the gas nas above described. a According to this combined process mixture requested for the synthetic manufacture of ammonia in countries which have ample supply of cheap hydro-electric power but where the coal price is comparatively the accompanying drawing I have shown diagrammatically anapparatus for carryingout the process;

Referringto the drawings, A designatesan electrolyticfplant in which water is decomposed into hydrogen and oxi'gen. The

oxygen-produced in the plant ismixed with air and steam and the mixture is supthe a paratus consists essentially of carbon dioxi e and hydrogen. Said gas mixture. is supplied to a scrubber or any other appara- 'tus D wherein the carbon dioxide is removed.

The remaining gas consisting essentially of hydrogen is collected together with the hy-' drogen gas coming from the electrolytic plant A. I

The economy of the process may be improved by preheating the gases supplied to the gas generator either by electrical heat or ,by means of the heat of the gases leavmq the gas generator or. by a combination of moth methods. 4

. What I claim is:

containing substantially hydrogen and nitro gen in "'c'ertainproport ons, which comprises electrolytically decomposing .water' into 0 a gen and hydrogen, using the oxygen tained together with steam and atmospheric air for continuously operating a water gasgenerator,-convert1ng the carbon monoxide of the water-gas generated b means of hydrogen free, removing the carbon dioxide and mixi-n the remaining 1 gas with the 1.-Method of producing a gas mixture steam into carbon dioxide w ile setting hydrogen 0 tained in the electrolysis, the

supply of electrolytic oxygen, atmospheric air and steam to the water gas generator be-' ing so regulated that the nitrogen of the generator gas will be about one third by volumeof the total quantity of hydrogen produced.

2. The ture'of hydrogenand nitrogen for synthesis of ammonia, which comprises electrolytically decomposing water, generating a gas mixture from incandescent carbonaceous material, air and the oxygen resulting from the aforesaid decomposition, to produce a mixture low innitrogen content, converting the carbon monoxlde content of such gasinto carbon -di-oxide by catalyticaction with steam, removing the resulting carbon di oxide, combining the remaining gas with the hydrogen from the electrolysis to a final methodof producing a gas product, and regulatin the production of the gas mixture to pro uce such final'prodnot having a content of hydrogen three times its nitrogen content, by the pure oxygen from the electrolysis. In testimony whereof I have signed my name.

FRAN S GEORGLHJJENRQTH. 

